The oldest species with a backbone has been identified, dating back more than 500 million years.
New studies confirm that the Unanozoan is the oldest known stem-shaped vertebrate.
For a long time, scientists have been confused about the gap in the fossil record that explains the evolution from invertebrates to vertebrates.
Vertebrates such as fish, amphibians, reptiles, birds, mammals, and humans have unique features, such as backbones and skulls. Invertebrates are animals without a backbone.
The process of transformation of invertebrates into vertebrates and what these first vertebrates looked like has been a mystery to scientists for centuries.
Currently, a Chinese research team is studying the Unanozoan, a creature that died out in the early Cambrian 518 million years ago.
Researchers have found evidence that the Yunnanzoan is the oldest stem-shaped vertebrate. The term vertebrate refers to vertebrates that are very closely associated with extinct but living vertebrates.
Over the years, when scientists have studied the evolution of vertebrates, the main focus of study has been on the structures that produce the face and neck, such as the pharyngeal arch, muscles, bones, and connective tissue.
The researchers hypothesized that the pharyngeal arch was an ancestor of vertebrates, such as the chordate lancet, which is an invertebrate close to vertebrates, and originated from unfused cartilage stalks.
However, it is not clear whether such anatomical structures existed in ancient times.
To better understand the role of the pharyngeal arch in ancient vertebrates, a Chinese team studied Yunnan soft fossils found in Yunnan.
Over the years, researchers have studied the Unanozoan and have come to various conclusions about how to interpret the anatomy of living things.
The Chinese team has set out to investigate previously unexplored methods of newly collected fossil specimens of animals from Yunnan and carry out high-resolution hyperfine and anatomical structure studies.
The 127 samples they studied contained well-preserved carbon deposits that allowed the team to observe hyperfine structures and perform detailed geochemical analyses.
The team used X-ray microtomography, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and energy dispersive X-ray spectroscopy on fossil samples.
Their findings, published in the journal Science, confirmed in several ways that Yunanozoans have cellular chondrocytes in the pharynx, which is characteristic of vertebrates.
This finding supports the theory that the Yunnanzoan is a stem-like vertebrate. The results of the study show that the Unanozoan is the oldest and most primitive relative of vertebrates.
During the study, the team observed that the seven pharyngeal arches of the Unanozoa fossils were similar to each other. All bows have segments and threads similar to bamboo.
All adjacent arches are connected by horizontal dorsal and ventral ridges that form the basket. The basket-shaped pharyngeal skeleton is a feature found today in fish without living teeth, such as lampreys and hagfish.
The lead authors of this study, Nanjing University and Tian Qingyi from the Nanjing Institute of Geological Paleontology, said:
“This means that the shape of the pharyngeal skeleton has a more complex early evolutionary history than previously thought.”
New anatomical observations made by the Chinese team in their study support the evolutionary placement of Yunnanzoan in the most basic part of the vertebrate tree of life.
Source: Metro
I have worked in the news industry for over 10 years. I have a vast amount of experience in covering health news. I am also an author at News Bulletin 247. I am highly experienced and knowledgeable in this field. I am a hard worker and always deliver quality work. I am a reliable source of information and always provide accurate information.
